The proposed research will deal with detailed light microscopic, ultrastructural and immunopathologic changes of the kidneys in human and experimental renal diseases. Human diseases will be studies by kidney biopsies and the morphologic findings will be correlated with clinical and laboratory data. In different glomerular diseases, particular attention will be directed not only to the glomerular capillaries and the mesangium but to the tubules and small arteries as well, on the assumption that changes in the two latter structures may play a role in the evolution of glomerular diseases to chronicity. Specific features of the renal involvement in SLE, amyloidosis, benign and malignant hypertension, scleroderma and drug addiction, as well as certain changes occurring in kidney allografts will be investigated. Experimental models of renal disease to be studied include: 1. Different types of hypertension with emphasis on the prehypertensive changes. 2. Glomerular damage induced by intraarterial injection of enzymes, vasoactive amines and other related substances and 3. The effects on the kidney and particularly on the tubules of parenterally injected Bence Jones' and other proteins. Methods to be used are histology, histochemistry, electromicroscopy including the use of electrondense and other tracers, and immunofluorescence microscopy. Other standard and specialized procedures to be done in relation to both human and experimental studies will be carried out in laboratories associated with these investigations and include urine analysis, serum creatinine, serum and urine protein studies, renin determinations and coagulation profiles.